It is well known to use balloon angioplasty catheters for the dilatation of various vessels of the human body and most particularly for opening stenotic arteries. It is also well known to place stents into vessels to maintain patency of that vessel. It is also well known to use a balloon catheter for imbedding a stent into the wall of the vessel to prevent stent migration.
It is typical to use separate catheters for vessel dilatation and for stent delivery. This requires one or more catheter exchanges which increases the time and cost for performing interventional procedures. Since the patient is typically in some discomfort during such procedures, it is also highly advantageous to the patient to make the interventional procedure as short as possible. Furthermore, removing a balloon angioplasty catheter after balloon dilatation can expose an intimal dissection that can make stent placement more difficult.
In U.S. Pat. No. 5,019,090, L. Pinchuk illustrates in FIGS. 13 to 18 a method for mounting a self-deploying stent on a balloon angioplasty catheter. However, Pinchuk's method functions only for self-deploying stents and not balloon expandable stents, and furthermore, his method requires the balloon to be advanced at least 3 cm beyond the distal end of the stenosis that is treated. That is not possible in many coronary arteries because of restrictions in the distal length of the coronary arteries. Furthermore, Pinchuk's method requires two additional steps, i.e. one is a further advancement of the balloon after balloon angioplasty is performed, and later pulling the balloon back within the deployed stent. Pulling back of the balloon catheter can cause the stent to be moved away from its optimal location. Additional steps in such a procedure require additional time which is generally undesirable. Furthermore, Pinchuk does not teach a means or method for the use of a guide wire through the center of the integrated catheter so as to guide it through the typically tortuous coronary vasculature. Still further, Pinchuk teaches an outer sheath with a blunt end whose operability can be defeated because of intimal dissection which often occurs as a result of balloon angioplasty or atherectomy. Still further, Pinchuk does not describe any structure at the catheter's proximal end for the introduction of fluids and a guide wire and for disallowing inadvertent release of the stent. Still Further Pinchuk requires two separate tubes for stent placement which is more complex than the use of a single tube for stent placement.
In U.S. Pat. No. 5,266,073 by W. H. Wall, there is described an "Angioplasty Stent" wherein a stent is mounted onto the exterior surface of a catheter, which catheter is placed coaxially over a conventional balloon angioplasty catheter. The Wall invention has several disadvantages and probably his design concept is not actually functional. By wrapping the stent around and onto the exterior surface at the distal end of the stent catheter, the stent can be easily dislodged as it is advanced through the tortuous coronary vasculature. Dislodgment would be less of a problem if close to 100% of the length of the stent is placed over the stent catheter; but in that case, the balloon at the distal end of the balloon angioplasty catheter could not be used to expand the stent. If, on the other hand, most of the length of the stent is placed beyond the distal end of the catheter onto which it is mounted so that the balloon could be used (though not efficiently) to expand the stent, then in that case the stent, as previously described, could easily become dislodged from the distal end of its catheter. Still further, having a stent mounted on the exterior surface of a catheter can cause a great deal of abrasion of the endothelial tissue on the inside surface of the arteries which is highly disadvantageous. Furthermore, the Wall invention could not be used with a self-expanding stent which stent has several functional advantages. Still further, Wall does not teach either a means to prevent distal embolization of the stent beyond the end of the balloon, nor does he teach a means for accurately positioning the stent onto the balloon.